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采用试验和仿真方法,研究了固体燃料冲压发动机(SFRJ)自持燃烧的主要影响因素。研究结果表明:SFRJ内为典型的扩散火焰,化学反应特征时间与反应物停留特征时间的比值是影响发动机自持燃烧的关键参数,该值越小,扩散火焰越稳定;本文研究工况下,较小的后台阶高度即可保证发动机实现自持燃烧,后台阶稳定火焰的物理原因是在固体燃料表面附近形成一个低速区,保证了固体燃料的分解燃烧,当台阶高度为0时,由于化学反应特征时间与反应物停留特征时间的比值迅速增加,SFRJ无法自持燃烧;台阶高度较小时,点火过程会对SFRJ的稳定燃烧产生影响,SFRJ可能会出现熄火复燃现象。
The main influencing factors of self-sustaining combustion of solid fuel ramjet engine (SFRJ) were studied by means of experiment and simulation. The results show that the ratio of characteristic reaction time to reactant residence time is the typical diffusion flame in SFRJ, which is the key parameter that affects the self-sustaining combustion of engine. The smaller the value, the more stable the diffusion flame. In this study, The small backstage height can guarantee the engine to achieve self-sustaining combustion. The physical reason for stabilizing the backstage flame is to form a low velocity zone near the solid fuel surface to ensure the decomposition combustion of the solid fuel. When the height of the step is 0, due to the chemical reaction characteristics SFRJ can not self-sustain combustion. When the height of step is small, the ignition process will affect SFRJ stable combustion, and SFRJ may appear the phenomenon of flameout and resurgence.